1. Field of the Invention
The present invention relates to a printing method, a printing system, a print server, and a computer readable recording medium on which a printing program is recorded. In particular, the invention relates to a printing method, a printing system, a print server, and a computer readable recording medium on which a printing program is recorded for using a plurality of image forming devices simultaneously in order to print more efficiently.
2. Description of the Related Art
There exist so-called office administration support service shops, where they receive print data from a client through recording medium such as a flexible disk or a network, and print it on paper using an image forming device such as a printer to provide the printed documents to the client. In order to print a large volume of documents in those shops, the work time can be shortened by means of using a plurality of printers in parallel. The method of using a plurality of printers for a single print job is called “Cluster Printing.” In the cluster printing, a print server for controlling a plurality of printers will be used. Let us assume a case of a cluster printing system using four printers connected to a print server. For example, when this cluster printing system receives a job consisting of 1000 pages, it divides the job to four groups of page 1 through 250, page 251 through 500, page 501 through 750, and page 751 through 1000, and prints each group of 250 pages using the four printers individually in parallel. This reduces the time to complete the entire print job to ¼ of what would be required when only one printer is used.
In the mean while, it is necessary for the print server to transfer the print data to each printer in coordination with printing speed of the printers in the cluster printing system if the printers do not have sufficient memory capacities to store the entire print data.
In a cluster printing system, however, the data transfer speed of the print server has to be high enough in correspondence with the number of printers as the total printing speed increases with the number of printers used. As the total printing speed increases due to the use of multiple printers, it could happen that the data transfer speed to each printer lags the printers' printing speed (PPM (page per minute), which is the unit of printing speed (number of pages of the image data to be processed per minute), will also be used herein as the unit of data transfer speed).
As there is a limit to the reading speed of the hard disk, which is the image storage device of a print server, the larger the data size of image data per page is, the lower the data transfer speed (PPM) from the print server is, and vice versa. When the data size of the image data is large, the data transfer speed (PPM) from the print server becomes lower, and the data transfer speed from the printer may consequently be lower than the printing speed of the printers.
As a result, the larger the image data size is and the higher the number of printers to which the data has to be transferred is, the higher the probability is for the data transfer speed to the printer becoming lower than the printing speed of the printers. Therefore, there was a problem of causing deficiency in a printing image as the transfer of the image data for a page is not completed during the printing of a page.